1. Field of Invention
The present invention relates to an improved wireless communications system. More particularly, the preferred embodiment of the invention concerns a multiple mode communications system, including special handsets designed to operate with standard analog or digital protocols when within the coverage of a standard cellular radiotelephone network, and to automatically switch to an enhanced cordless mode that operates with unique protocols when within the coverage area provided by independent, low power "pico" cells that are connected to the wireline telephone network. The term "pico" is used herein to suggest a smaller size than conventional cellular radio telephone cells. Pico cells are provided at customer selected locations to cooperate with a framework of overlay cells that operate independently of the cells of the cellular network.
This overlay cell framework allows the service provider to exercise complete control over the operation of each special handset and the pico cell system by means of service control units and host stations. The standard cellular system can be further enhanced by the addition of zone identifier overhead messages which are ignored by standard handsets but interpreted by the special handsets to inform those customers continuously of the special handset's current operating mode.
2. Description of Related Art
There has long been a recognized need for ubiquitous telecommunications services wherein each customer is assigned a personal service number and provided with suitable equipment which will permit the customer to have two-way communication capability (i.e., the ability to make and receive calls) regardless of the customer's changing location.
Systems that extend beyond traditional wireline telephone service have been developed in order to more closely achieve this capability from a technical perspective. For example, recent innovations in paging, standard cordless within the home telephone service, cellular telephone service and personal communications systems are well known. The designs of such systems all comprise efforts to cost effectively satisfy the need for ultimate ubiquitous service. However, each system has well recognized technical and cost disadvantages which cause it to fall short of providing ubiquitous telecommunications service.
For example, conventional systems control the operation of remote equipment via remote programming. However, such conventional systems require original programming to establish a phone system identity, such as a Mobile Identification Number (MIN), which may be later used to engage in calls that provide remote programming. This is an undesirable remote programming technique because it prevents the original programming from occurring remotely. Consequently, an entire complex and expensive infrastructure is provided to deal with original programming for remote equipment through physical access to the equipment.
In addition, conventional cellular systems monitor power levels of transmitted signals to determine whether signal levels are sufficiently high to warrant the provision of communication services. Such conventional systems have a relatively low access threshold because they do not wish to deny communication services to any potential user and forego the revenues potentially achievable therefrom. However, conventional cellular systems may handoff or drop a call immediately after accepting access from a handset with a weak signal. This is an undesirable technique when applied to small cells that do not support handoffs or wish to minimize handoff overhead communications because it leads to dropping or handing-off calls immediately upon access.
Furthermore, conventional cellular systems are designed so that users are not aware when their calls are about to be dropped by a cell. When a call is dropped by one cell, hopefully another cell is available to accept the call through a handoff process. But, in conventional and other cellular systems, the availability of another cell is not assured. This is an undesirable operational technique because calls are dropped without warning users in situations where users may be able to take steps to prevent the call from being dropped.
Moreover, when conventional systems provide alerting signals, such as call waiting sounds and others, to users during a call, such alerting signals are often configured so that both parties to the call are aware of the alerting signal. This too is an undesirable operational technique. The party in the call who is not being alerted generally has no need to know of the alert. When this other party becomes aware of an alert which has no meaning to him or her, confusion often results and the flow of a conversation is often unnecessarily disrupted.
Still further, conventional systems are designed merely to provide services through handsets when they are able to do so. They generally fail to recognize that a variety of communication services may be available through a variety of different communication systems, such as multiple cellular systems and a land-line service. They further fail to integrate the variety of services in a common handset and to provide meaningful information to a user regarding the various communication service options which may be available through the handset from time to time.
Accordingly, a need still exists for an improved communications system that comes closer to providing ubiquitous communications service to customers than existing systems.